Growth of forests 'restricted' since the hot summer of 1976
24 July 2013 Last updated at 13:40 BST
The sizzling summer of 1976 caused permanent changes to British forests, new research suggests.
Scientific work was carried out at Lady Wood Park in the Wye Valley. The 111 acre site is a national nature reserve and is attractive to researchers because it has been deliberately unmanaged since 1945.
The study found growth of the trees is still restricted more than 30 years later.
Sian Lloyd went to the Wye Valley in Monmouthshire to see the damage.